This app was mentioned in 7 comments, with an average of 1.43 upvotes
https://play.google.com/store/apps/details?id=com.hybrid.stopwatch&hl=en_US
This is the Android version, hopefully this helps.
I just tried it, works fine for me. Loud alarm and screen came on when timer expired. I'm also using 5.1.1. Have you tried a third party timer? I like this one?
https://play.google.com/store/apps/details?id=com.hybrid.stopwatch
Hybrid Stopwatch is what I use. It's great because you can set different timers which is great for me at the gym.
I haven't tried these yet but they might help:
https://play.google.com/store/apps/details?id=com.hybrid.stopwatch
https://play.google.com/store/apps/details?id=com.jee.timer&hl=en&gl=US
You could label each timer with a kids name. Add time as rewards.
you may find
Stopwatch Timer by Javier Salmona fits your requirements.
https://play.google.com/store/apps/details?id=com.hybrid.stopwatch
Χαίρομαι που το ακούω :)
για κάποιο λόγο τα link δεν λειτουργούν στο pdf.
timer + / iphone => https://itunes.apple.com/us/app/timer+/id391564049?mt=8
stopwatch timer / android => https://play.google.com/store/apps/details?id=com.hybrid.stopwatch&hl (δεν έχω android atm για να δω αν κάνει το app αλλά μετά από ένα σύντομο google search, I think it seems legit) bonus: timer / windows phone => https://www.microsoft.com/en-us/store/apps/timer/9wzdncrfhvfd
επίσης έγω φτιάχνω μία η άλλη spreadsheets για εμένα κάθε μήνα. Αν θες πες μου να σου κάνω pm τα Νοεμβρίου/Δεκεμβρίου